HUDSON RIVER PCBs REASSESSMENT RI/FS
PHASE 2 HUMAN HEALTH RISK ASSESSMENT
SCOPE OF WORK
JULY 1998
U. S. Environmental Protection Agency
Region II
290 Broadway
New York, N. Y. 10007
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£
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 2
290 BROADWAY
NEW YORK. NY 10007-1866
2 3 1998
To All Interested Parties:
The U.S. Environmental Protection Agency (EPA) is pleased to release the Scope of Work for
the Human Health Risk Assessment for the Hudson River PCBs Superfund site Reassessment.
This document describes the procedures that EPA will use to develop the baseline human health
risk assessment for the Hudson River PCBs site. The risk assessment will quantify both
carcinogenic and non-carcinogenic health effects from exposure to polychlorinated biphenyls
(PCBs) in the Upper and Mid-Hudson River. The assessment will evaluate both current and
future risks based on the assumption of no remediation or institutional controls (e.g., fishing
restrictions).
The Scope of Work for the Ecological Risk Assessment for the site will be released in September
1998. The Human Health Risk Assessment and the Ecological Risk Assessment will be released
in August 1999, after modeling work essential to the reports is completed.
Please note that EPA released a Preliminary Human Health Risk Assessment in the Phase 1
Report in August 1991. The Human Health Risk Assessment to be released in August 1999 will
supercede that effort. It should also be noted that the Agency has already completed numerous
tasks outlined in the Scope of Work. Nevertheless, a comprehensive scope of work for the risk
assessment is being provided at this time for simplicity in understanding the issues.
EPA will accept comments on the Scope of Work for the Human Health Risk Assessment until
Monday, August 31,1998. Comments should be marked with the name of the report and should
include the report section and page number for each comment. Comments should be sent to:
Douglas Tomchuk
USEPA - Region 2
290 Broadway - 20* Flooi
New York, NY 10007
Attn: HHRA SOW Comments
EPA will present the outline for conducting the Human Health Risk Assessment along with the
findings of the Low Resolution Coring Report at a joint liaison group meeting in Albany, New
York. Notification of this meeting was sent to liaison group members several weeks prior to the
meeting. In the interim, between the release of this document and the end of the comment period,
EPA will hold two public availability sessions to further answer public questions regarding this
document as well as the Low Resolution Coring Report. These sessions will be held on
Wednesday, August 19, 1998 at the Holiday Inn Express in Latham, New York from 2:30 to
4:30 p.m. and from 6:30 to 8:30 p.m., and on Thursday, August 20, 1998 from 6:30 to 8:30 p.m.
at Marist College hi Poughkeepsie, New York.
R«cycl«d/R«cycUbl« •Printed with Vegetable Oil Based Inks on Recycled Paper (40% Postconsumer)
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If you need additional information regarding this scope of work, the availability sessions or with
respect to the Reassessment in general, please contact Ann Rychlenski, the Community Relation
Coordinator for this site, at (212) 637-3672.
Sincerely yours,
Richard L. Caspe, Director
Emergency and Remedial Response Division
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HUDSON RIVER PCBs REASSESSMENT RI/FS
PHASE 2 HUMAN HEALTH RISK ASSESSMENT
SCOPE OF WORK
JULY 1998
U. S. Environmental Protection Agency
Region II
290 Broadway
New York, N. Y. 10007
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TABLE OF CONTENTS
Page
I. Historical Overview of Risk Assessment for the Hudson River and 1
the Risk Assessment Process
1. Introduction 1
2. Background 1
2.1. The Site 1
2.2. Phase 2 Reassessment and Risk Assessment 2
3. Definition of Risk Assessment 2
4. Results of Phase 1 Risk Assessment 4
5. Changes in EPA Risk Assessment Guidance Since the Phase 1 4
Risk Assessment
II. Upper Hudson River Risk Assessment Scope of Work 6
1. Plan, Synopsis & Objectives 6
2. Exposure Assessment 7
A. Concentration of PCBs in Fish 7
B. Fish Consumption Rates for the Upper Hudson River 7
C. Species-Specific Fish Ingestion 9
D. Exposure Duration 10
E. PCB Cooking Losses 11
F. PCB Concentrations for Deterministic and Monte Carlo Analyses 12
G. Exposure Calculations from Fish Ingestion 13
H. Other Exposure Pathways 13
I. Calculation of Total Risks and Hazards 14
3. Toxicitv Assessment 14
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Pat
4. Risk Characterization 14
A. Calculation of Point Estimates of Central Tendency and 15
High-End Individual Risks
B. Risks for Highly Exposed Subgroups 15
C. Monte Carlo Analysis 15
D. Additional Qualitative Discussions 16
E. Presentation of Results 16
III. Mid-Hudson River Human Health Risk Assessment 17
1. Plan. Synopsis & Objectives 17
2. Exposure Assessment 17
A. Fish Concentration Data 17
B. Fish Consumption Rates for the Mid-Hudson River 17
C. Species-Specific Fish Ingestion 18
D. Exposure Duration 18
E. PCB Cooking Losses 19
F. PCB Concentrations for Deterministic and Monte Carlo Analyses 19
&.^ - Exposure Calculations From Fish Ingestion 20
H. Other Exposure Pathways 21
I. Calculation of Total Risks and Hazards 21
3. Toxicity Assessment 21
4. Risk Characterization 22
A. Calculation of Point Estimates of Central Tendency and 22
High-End Individual Risks
B. Risks for Highly Exposed Subgroups 22
C. Monte Carlo Analysis 23
D. Additional Qualitative Discussions 23
E. Presentation of Results 23
IV. References 24
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I. HISTORICAL OVERVIEW OF RISK ASSESSMENT
FOR THE HUDSON RIVER AND THE RISK ASSESSMENT PROCESS
1. Introduction
The purpose of this document is to outline the procedures that will be used by U.S. EPA
(EPA) in developing the baseline human health risk assessment for the Hudson River as required
under the National Oil and Hazardous Pollution Contingency Plan (U.S. EPA, 1990). The
assessment will quantify both carcinogenic and non-carcinogenic health effects from exposure to
polychlorinated biphenyls (PCBs) in the Hudson River and follow appropriate EPA risk
assessment policies and guidance. The assessments will evaluate both current and future risks
based on the assumption of no remediation or institutional controls (U.S. EPA, 1990).
The Scope of Work for the ecological risk assessment will be provided separately.
Two human health risk assessments are planned. The Upper Hudson River risk
assessment will cover the area between Hudson Falls and the Federal Dam in Troy, New York to
Fort Edward. New York, a length of approximately 40 river miles (see Section II). The Mid-
Hudson River risk assessment will cover from Albany, New York to Poughkeepsie. New York a
length of approximately 83 river miles (see Section III). The risk assessments will be
developed using similar methodologies, but may be developed at different times.
The risk assessments will include data collected during the initial Remedial Investigation/
Feasibility study conducted in the late 1970's and early 1980's and data collected during the
Reassessment Remedial Investigation and Feasibility Study (RI/FS) started in 1990. The
assessment will rely primarily on data from the Phase 2 Investigation contained in the database
for the Hudson River PCBs Reassessment RI/FS in the following documents: the Database
Report (U.S. EPA. 1995a); the Preliminary Model Calibration Report (U.S. EPA. 1996a); the
Data Interpretation and Evaluation Report (U.S. EPA. 1997d); and the Baseline Modeling
Report currently being developed.
Individual components of the proposed approach may be revised if additional data are
identified in the course of preparing the risk assessment.
2. Background
2.1. The Site. The Hudson River PCB Superfund Site extends from Hudson Falls, New
York to the Battery (at the southern tip of Manhattan) in New York. The site covers
approximately 200 river miles.
From 1957 through 1975, between 209,000 and 1,300,000 pounds of PCBs were
discharged to the Upper Hudson River from two General Electric facilities; one located in Fort
Edward, New York and the other in Hudson Falls. New York (U.S. EPA, 1991). In 1977. the
1
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manufacture and sale of all PCBs within the U.S. was stopped under provisions of the Toxic
Substances and Control Act (U.S. EPA, 1978).
In 1973, the Fort Edward Dam was removed and subsequently the downstream move-
ment of PCB contaminated sediments was greatly facilitated (U.S. EPA. 1991). Because of
potential human health risks due to consumption of PCB-contaminated fish, the New York State
Department of Environmental Conservation (N YSDEC) banned fishing in the Upper Hudson
River and limited the recommended number of fish meals consumed for specific species in the
Lower Hudson River (NYSDOH, 1991). In 1976, the commercial striped bass fishery in the
Hudson River was closed based on elevated PCB levels in the bass. The ban on fishing in the
Upper Hudson River was subsequently changed to a "catch and release'' program in August 1996.
In 1984, EPA issued a Superfund Record of Decision (ROD) for the site. The ROD
required: 1) an interim No Action decision concerning river sediments; 2) in-place capping,
containment and monitoring of remnant deposit sediments; and 3) a treatability study to evaluate
the effectiveness of removing PCBs from the Hudson River water (U.S. EPA, 1984).
2.2. Phase 2 Reassessment and Risk Assessment. In December 1990, U.S. EPA
Region II began a reassessment of the No Action decision for the Hudson River sediments based
on a request by NYSDEC to do so, and by the requirements by the Superfund Amendments and
Reauthorization Act of 1986 to conduct reviews for sites where contamination remains on site.
The reassessment consisted of three phases: interim characterization and evaluation; further site
characterization and analysis; and a Reassessment Remedial Investigation and Feasibility Study.
This report presents an outline of the proposed Human Health Risk Assessment that will be
developed during the Reassessment for the Upper and Mid-Hudson River. Individual
components of the proposed approach may be revised if additional data are identified in the
course of preparing the risk assessment.
3. Definition of Risk Assessment
The goal of the Superfund human health evaluation process is to provide a framework for
developing the risk information necessary to assist in the determination of possible remedial
actions at a site. EPA uses risk assessment as a tool to characterize the contaminants, evaluate
the toxicity of the chemicals, assess the potential ways in which an individual may be exposed to
the contaminants, and characterize the risks (U. S. EPA, 1989). The risk assessment is designed
to evaluate the current and future risks to the Reasonably Maximally Exposed Individual and the
Average Exposed Individual for both cancer and non-cancer health effects.
Risk assessment was defined by the National Academy of Sciences (National Research
Council. 1983) as involving one or more of the following four steps:
• Hazard Identification - an assessment of the types of adverse health effects (i.e., cancer or
non-cancer) associated with exposure to chemical(s).
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• Dose-Response - the relationship between the magnitude of the exposure and the adverse
effects.
• Exposure Assessment - an estimate of the magnitude of actual and/or potential human
exposures, the frequency and duration of these exposures, and the pathways (i.e.,
inhalation, ingestion. and dermal contact) by which people are potentially exposed.
• Risk Characterization - a summary of the results from the first three portions of the
assessment (both quantitative and qualitative) and a discussion of the uncertainties.
The quantitative assessment of carcinogenic risks involves the evaluation of lifetime daily
average exposure levels and application of toxicity factors reflecting the carcinogenic potency of
the chemical. Excess lifetime cancer risk is calculated as:
Risk = Cancer Slope Factor (CSF) X Chronic Daily Intake (GDI).
The cancer slope factor is an estimate of an upper-bound probability of an individual
developing cancer as a result of a lifetime of exposure to a particular level or dose of a potential
carcinogen. The cancer slope factor is expressed in units that are the reciprocal of those for
exposure i.e., (mg/kg-day)"1. The exposure levels are expressed as the chronic daily intake
averaged over a lifetime of PCB exposure from the river. The exposure is expressed in units of
mg of PCB intake per kilogram (an equivalent of 2.2 Ibs) of human body weight per day (mg/kg-
day). Multiplication of the exposure level by the CSF yields a unitless estimate of cancer risk.
The risk estimate for cancer reflects the incremental increase in the probability of developing
cancer following site-specific exposure. The acceptable risk range identified in the NCP (U.S.
EPA, 1990) is 10'4 to 10'6 (or an increased probability of developing cancer of 1 in 10,000 to 1 in
1.000.000).
The evaluation of non-cancer health effects involves a comparison of average daily
exposure levels with established Reference Doses (RfDs) to determine whether estimated
exposures exceed recommended limits. A Reference Dose is defined as "an estimate, with
uncertainty spanning perhaps an order of magnitude or greater) of a daily exposure level for the
human population, including sensitive subpopulations, that is likely to be without an appreciable
risk of deleterious effects during a lifetime" (U.S. EPA, 1989). The comparison is expressed as
a Hazard Quotient (HQ), which is the ratio of the estimated exposure to the RfD. When the HQ
exceeds a value of 1, unacceptable exposures may be occurring. Both exposure levels and RfDs
are typically expressed in units of mg of PCB intake per kilogram of body weight per day
(mg/kg-day). Unlike the evaluation of carcinogenic effects, exposures of less than lifetime
duration are not averaged over an entire lifetime.
The risk characterization presents the calculated risks and hazards from exposure to
PCBs and associated uncertainties. The risk characterization is used by risk managers in their
decision-making process.
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4. Results of Phase 1 Risk Assessment.
In 1991, EPA issued the Phase 1 Report - Interim Characterization and Evaluation for the
Hudson River PCB Reassessment Remedial Investigation/Feasibility Study including a
quantitative risk assessment for the Upper Hudson and a qualitative risk assessment for the
Lower Hudson River (U.S. EPA, 1991). The Phase 1 Risk Assessment determined that the
potential chemical risks from PCBs in fish alone were the major source of health risks associated
with exposure to site related contaminants. A brief summary of the results for the Upper and
Lower Hudson River assessments are summarized below.
The Upper Hudson River human health risk assessment evaluated current and potential
risks from ingestion offish. The risks from ingestion of fish were found to exceed EPA's cancer
risk range of 10"* to 10 ~6 (an increased probability of developing cancer of 1 in 10.000 to 1 in
1,000?000) and 1 for non-cancer (indicating an exceedence of the Reference Dose). The risks
from drinking water were within the risk range. Risks from dermal exposure to river sediment.
incidental ingestion of river sediment, and dermal contact with river water were within the risk
range. Risks from other pathways including ingestion of vegetables, meat, etc. and inhalation
exposures could not be quantified at that time based on insufficient data.
The Lower Hudson River human health risk assessment qualitatively evaluated current
and potential risks from ingestion of fish based on the findings in the Upper Hudson River. The
assessment concluded that the risks from ingestion of fish would be similar to those found in the
Upper Hudson River.
5. Change?"in-EPA Risk Assessment Guidance Since The Phase 1 Risk Assessment.
Since the Phase 1 risk assessment EPA issued several new risk assessment policies and
guidance documents (U. S. EPA, 1992a.b; 1995a-c: 1996a-c; 1997a-c; and 1998a-c). A brief
summary of the new documents and their impact on the risk assessment are provided below.
• The Oral Reference Dose for Aroclor 1016 used in the original assessment was changed
from 1 x 10'4 to 7 x 10'5 on January 1, 1993 (U.S. EPA, 1998a). This RfD is a more
stringent RfD than the RfD used in the original assessment.
• A new Oral Reference Dose for Aroclor 1254 was developed and added to the Integrated
Risk Information System (IRIS) on October 1, 1994 (U.S. EPA, 1998b). This provides
another toxicity value for evaluating non-cancer hazards.
• Risk Assessment Guidelines on Exposure Assessment were issued in 1992 (U.S. EPA.
1992a). These guidelines define the "high end" of population exposure between the 90th
and 99.9th percentiles with the 99.9th percentile considered a bounding estimate.
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Risk Characterization guidance was released in 1992 (U.S. EPA, 1992b) and updated in
1995 (U. S. EPA, 1995b). The guidance recommends the Agency adopt the values of
transparency, clarity, consistency and reasonableness in the development of risk
characterizations including better characterizations of uncertainty.
Revised Carcinogen Risk Assessment Guidelines were proposed in 1996 (U. S. EPA,
1996b). The proposal includes changes in the method of extrapolating from animals to
humans to be more consistent with approaches used by other federal Agencies. For PCBs
this resulted in a reduction in the cancer slope factor by a factor of 2 based on the animal
studies used in the extrapolation from animals to humans (U.S. EPA, 1996c). The
guidance also changed the categories for classifying the carcinogenic potential of
chemicals. The assessment will use the new cancer slope factor and the revised
carcinogenic classification, as appropriate.
The Agency reassessed the toxicity data on the potential carcinogenic potency of PCBs in
1996 (U. S. EPA, 1996c). The reduction in the cancer slope factor for fish ingestion from
7.7 mg/kg-day to 2.0 mg/kg-day reflects the re-evaluation of the available animal toxicity
data (a factor of approximately 2) and the new policy for extrapolating from animals to
humans (a factor of approximately 2) as discussed in the proposed Cancer Guidelines
(described above, U.S. EPA, 1996b).
The reassessment of cancer toxicity resulted in new cancer slope factors for ingestion of
fish of 2.0 (mg/kg-day)-1, for inhalation of PCBs of 0.4 (mg/kg-day)-1, and 0.07 (mg/kg-
day )•' if a congener or isomer analysis verifies the absence of congeners with more than
four chlorines (concentration less than 0.5% of total PCBs), and for dermal of 0.4
(mg/kg-day)'1 if no absorption factor is applied. The Phase 1 risk assessment used a oral
cancer slope factor of 7.7 (mg/kg-day)"' for ingestion offish. Inhalation risks were not
evaluated based on a lack of toxicity data at the time of the Phase 2 assessment.
The Agency released "Guiding Principles for Probabilistic Analysis" in 1997 (U. S. EPA,
1997a). These guidelines set forth basic approaches for developing a probabilistic risk
assessment and determining when a probabilistic assessment is appropriate. Based on the
extent of data from the reassessment a probabilistic analysis will be performed to evaluate
variability and uncertainties in the cancer and non-cancer risk assessments.
The Agency released the "Special Report on Environmental Endocrine Disruption: an
Effects Assessment and Analysis (U.S. EPA, 1997b)" and the Science Policy Council's
Interim Position on Endocrine Effects (U.S. EPA, 1997c)" in 1997. These documents
summarize the existing data on the potential effects of chemicals with endocrine effects
and the need for additional research. The assessment will qualitatively address endocrine
effects based on this guidance.
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II. UPPER HUDSON RIVER RISK ASSESSMENT SCOPE OF WORK
1. Plan, Synopsis & Objectives
This Scope of Work details the issues and tasks that EPA will consider in the
development of the Upper Hudson River Phase 2 Human Health Risk Assessment. The Scope of
Work is described in the format of the presentation of the final report. Individual components
of the proposed approach may be revised if additional data are identified in the course of
preparing the risk assessment.
The toxicity values, the Cancer Slope Factors and Reference Doses for cancer and non-
cancer health effects will be obtained from the EPA's Integrated Risk Information System
(IRIS). IRIS provides the Agency's consensus review of toxicity data (U.S. EPA, 1998a-c). The
assessment will also qualitatively address endocrine effects based on the Agency's "Special
Report on Environmental Endocrine Disruption: an Effects Assessment and Analysis" (U.S.
EPA, 1997b) and recent scientific publications. Although EPA is currently supporting
significant research in this area, the available data are insufficient to support a quantitative
assessment of endocrine effects. Therefore, a qualitative assessment and discussion in the
uncertainty section on endocrine effects will be presented.
The exposure portion of the risk assessment will be divided into two parts. The first part
will involve calculating Lifetime and Daily Doses of exposure for individuals using standard
exposure equations (U.S. EPA, 1989) where the exposure parameters (ingestion rate, exposure
duration, body weight, etc.) are calculated using single point estimates. This method is the same
as the approach used in the Phase 1 risk assessment and is described in the Risk Assessment
Guidance for Superfund - Part A (U.S. EPA, 1989).
The second analysis involves a probabilistic risk analysis using the most commonly used
method termed Monte Carlo analysis (U.S. EPA, 1997a). The probabilistic risk analysis presents
risk as a range of values instead of a single point value because individuals may have different
responses. The probabilistic risk analysis attempts to capture information on both uncertainties,
(i.e., that which is not known) and variability (i.e., observed differences attributable to true
differences in a population or exposure parameter).
The Monte Carlo analysis involves a number of steps that are briefly described below.
First the scientific literature will be reviewed to identify studies that can provide information on
the variability of each of the exposure parameters (ingestion rate, exposure duration, body
weight, etc.). Second, using this information a model will be developed that specifies the
possible range of exposure values. Third, a simulation is carried out using computer programs
whereby the distribution of possible outcomes is generated by letting a computer recalculate the
worksheet over and over again, each time using different randomly selected sets of exposure
values from the probability distributions for each parameter. Fourth, the results from the analysis
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will be combined with the appropriate toxicity value and graphed and presented in the final risk
assessment.
The final Phase 2 report for the Upper and Mid-Lower Hudson River will include a brief
(1-2 pages) synopsis of the 1991 risk assessment. The Phase 2 report will contain an
introduction describing the objectives of the Phase 2 risk assessment, namely to confirm the
findings from Phase 1, that risks from fish ingestion outweigh other pathways of exposure, and to
provide both point and probabilistic estimates of risk associated with human consumption offish.
2. Exposure Assessment
A. Concentration of PCBs in Fish
The fish concentrations will be developed using data from the Hudson River Database
report (U. S. EPA, 1995a); the Preliminary Model Calibration report (U. S. EPA. 1996a); the
Data Interpretation and Evaluation report (U. S. EPA. 1997d); and the Baseline Modeling report
under development. The risk assessment will summarize the results of these analyses and
explain procedures used in developing the fish concentration data.
B. Fish Consumption Rates for the Upper Hudson River
Fish ingestion rates are waterbody specific and depend on a number of factors including
weather, available fish species, angler (man, woman or child who fishes), preference for specific
species, impact of fishing bans, and distance of the angler from the water body. Numerous
scientific studies of various water bodies (lakes, rivers, streams, etc.) were conducted to identify
fishing patterns (frequency, fishing practices, fish species preference, etc.) and fish consumption
rates (amount of fish consumed on a daily basis). Many studies involve interviews with anglers
at the dockside requesting information about the fishing activities (fish preference, consumption
rates, cooking methods, age, gender, frequency of fishing the specific water body, etc.). This
survey method provides information on both licensed and un-licensed anglers depending upon
who is interviewed. Other studies involve sending questionnaires to licensed anglers requesting
information on fishing practices, preferred rivers, lakes or streams, fish consumption, and other
information. The results from both surveys are evaluated, statistically analyzed, and presented in
the published scientific literature, government reports, or reports from organizations.
Using fish consumption information, the risk assessment will include a characterization
of a distribution of fish consumption rates for the Upper Hudson River including high-end and
central tendency (average exposure) point estimates identified as the 95th and 50th percentiles,
respectively from the selected distribution of data on fish consumption. Because fish ingestion
rates are waterbody-specific. the review will be limited to a review of studies of anglers in the
Northeast inland flowing waterbodies. Based on a preliminary review of the available scientific
literature, the focus will be primarily on the Connelly studies of New York State anglers
(Connelly et al., 1990, 1992, and 1996) since they provide comprehensive information about
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angler activities including fish ingestion rates from numerous New York waterbodies which
share similarities with the Upper Hudson River. The 1992 Connelly study provides detailed
information about 1,030 licensed New York anglers, including their total consumption of
sport-caught fish in 1991, the number offish caught and consumed according to species and
fishing location, the number of days fished in 1991. the age anglers began fishing, and
background demographic information e.g., socioeconomic, age, gender, etc. (Connelly et al..
1992). A previous study by Connelly in 1990 asked 10,314 licensed New York anglers about
their total yearly fish consumption (from all sources), the number of days fished in 1988, the
distance traveled to fish, cooking preferences, and whether anglers had a fishing license in the
previous three years (Connelly et al., 1992). The 1996 survey objective was to provide accurate
estimates offish consumption among Lake Ontario anglers and to evaluate the effect of Lake
Ontario health advisory recommendations (Connelly et al., 1996). The analysis offish ingestion
rates will be based on an evaluation of fish rates from the Connelly databases for all flowing
water bodies.
The evaluation will also consider fish ingestion information from the Clearwater survey
of Hudson River anglers (Barclay, 1993), the ChemRisk study of licensed Maine anglers
(ChemRisk, 1991), and other recent creel surveys (Peterson, 1998 and ongoing 1998 NYSDOH
survey), based on availability. Evaluation of more than one fish ingestion study allows
consideration of the consistency among studies and comparison of rivers with and without
fishing bans. This results in an increased level of confidence in the use of the Connelly data
(Connelly et al., 1990, 1992, and 1996).
The following section describes other surveys (mentioned above) and their potential
application in tfie'risk assessment:
• The Clearwater survey included 336 shore-based anglers interviewed at 20 different
locations along the Hudson, including 3 sites in the Upper Hudson, during 1991 and 1992
(Barclay, 1993). The anglers were asked how often they fished and ate fish from the
Hudson in the previous week and month, and the extent to which they shared their catch
with other relatives and friends. While the Clearwater survey is less comprehensive than
the Connelly dataset, the results are useful because both licensed and non-licensed
anglers were surveyed. It is the only available study specific to the Hudson.
• The ChemRisk study involved collecting survey data from 1,612 licensed Maine anglers
who completed questionnaires asking the number of fishing trips they had taken in 1990
and the number of each fish species caught and consumed (ChemRisk, 1991). The
ChemRisk data will be evaluated for similarities between the Maine and New York water
bodies (i.e., water body size, water temperature, dominant harvest species, and the
percent of water bodies with fishing bans) to determine relevance to the Hudson River.
• Other surveys including the Peterson study (1998) and the NYSDOH on-going survey of
anglers will also be evaluated. The Peterson study (1998) evaluated striped bass
8
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harvested from the Hudson River. The NYSDOH on-going survey of recreational anglers
activities on the Hudson River will also be evaluated depending when the report is
completed.
Review of the scientific literature indicates there are a number of other issues that will
need to be considered in evaluating angler surveys. These issues include:
• Recall bias in questionnaire responses, including the assertion based on studies of
anglers where fish were measured at the time of catch that people overestimate positive
events i.e., anglers might remember catching bigger fish.
• Bias toward frequent anglers in creel surveys (surveys of people fishing) where an
interviewer is more likely to interview the angler who spends more time fishing.
• Seasonal limitations/variations on the fishing season, where some anglers might limit
fishing to warm weather conditions and not engage in ice fishing.
• Impact of considering data from only licensed anglers in the Connelly and ChemRisk
mail surveys as compared to non-licensed anglers.
• Freshwater fish ingestion rates for children since children under the age of 14 are not
required to have fishing licenses within New York State and other states.
For the purpose of this risk assessment, a hypothetical study population will be defined
as any individual who would consume self-caught fish from the Hudson River at least once per
year in the absence of a fishing ban. The population in question will therefore include a range of
infrequent to very frequent anglers, who may fish for sport (recreational) or for sustenance (food
supplement). To the extent possible both licensed and unlicensed anglers will be included in the
assessment: however, it is noted that information about unlicensed anglers is limited to the
Clearwater survey (Barclay, 1993) and the Peterson survey (Peterson. 1998). Attempts will not
be made to distinguish between the subpopulations of highly exposed or lesser exposed anglers.
as these subpopulations will be represented in the distributions of risk generated in the Monte
Carlo analysis. The analysis of the various creel surveys and the basis for selection will be
documented in the risk assessment, as appropriate.
C. Species-Specific Fish Ingestion
This step will involve the characterization of species-specific fish ingestion rates for
anglers fishing the Upper and Mid-Hudson River, using data from a subset of "Hudson-like"'
rivers and streams from the Connelly databases (Connelly et al.. 1990. 1992, and 1996). based on
the species offish present. To generate this information, the data from the Connelly (Connelly et
al.. 1990. 1992 and 1996) and Clearwater studies (Barclay, 1993) studies will primarily be used.
Species-specific data will be derived from a subset of "Upper and Mid-Hudson-like" rivers and
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streams from the Connelly database for all flowing water bodies. ChemRisk's Maine survey
(ChemRisk, 1991) may also be useful, depending on the similarities between the Maine water
bodies and the Hudson River. The relative contribution of each species to an individual's total
fish intake from the Hudson will be characterized and confirmed based on an analysis of the
consistency of the results with all the available data and that the species are present in the
Hudson. If any species offish are present in the Hudson and likely to be eaten, but modeled
PCB concentration data is lacking, estimates of PCB levels based on the fat content of the fish
and available concentration data from other similar species will be developed.
Although theoretically, there may be ethnic groups or small subpopulations of anglers
that preferentially eat different species of fish than the general angling population, there is no
data available on this issue. This issue may be addressed as part of the uncertainty analysis, the
second tier of the Monte Carlo analysis, using professional judgment to characterize possible
species-specific consumption rates.
D. Exposure Duration
An evaluation of the available data on county mobility and angling cessation will be
performed to develop a realistic exposure duration for fishing in the Upper Hudson River. While
Superfund risk assessments typically use the length of time that an individual remains in a single
residence as an exposure duration, such an estimate is not likely to be a good predictor of angling
duration, since an individual may move into a nearby residence and continue to fish in the same
location, or an individual may chose to stop angling irrespective of the location of their home.
A more reasonable approach to estimate exposure duration is to evaluate the average
length of time before an individual moves far enough away from the Hudson so that continued
fishing in the Hudson would be unlikely. Connelly et al. (1990) reported that anglers traveled a
mean distance of 34 miles to fish in the Upper and Lower Hudson River in 1988; however, there
was considerable variability in the distances that people were willing to travel. Also, it is unclear
how relevant this mean distance of 34 miles is for the Upper Hudson River risk assessment, since
the Connelly survey was conducted while there was a fishing ban in effect in the Upper Hudson.
and the traveling distance results were combined for the Upper and Lower Hudson. The size of
counties will also be evaluated relative to the 34 mile distance. Therefore, as a reasonable
approximation, the assessment plans to assume that Upper Hudson River anglers fish in the
Upper Hudson as long as they live within one of the counties bordering the Upper Hudson, and
that once they move outside of the bordering counties, they would no longer be willing to travel
the longer distance to the Upper Hudson to fish. The assessment plans to analyze local and
national county mobility data (the In-Migration and Out-Migration Special Project Files from the
Census Bureau) as well as national census information such as the length of time people live in a
single residence (from the Census Bureau summary tape, population file 1 A, U. S. Department of
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Commerce. Bureau of Census, 1992) to generate a reasonable estimate of how long people
remain living within the counties bordering the Upper Hudson.
To the extent possible, the assessment also will attempt to incorporate the likelihood that
an angler may voluntarily choose to stop fishing, based on an analysis of the percent of licensed
anglers in the general New York State population at each age. Such an analysis may be possible
using census data to determine the number of individuals in each age group (Bureau of the
Census, 1992) and the Connelly data (Connelly et a/., 1990, 1992 and 1996) to determine the
number of licensed anglers in each age group. It is suspected that, generally, anglers are highly
dedicated to their sport, and few voluntarily stop fishing.
To the extent possible, the assessment will investigate whether the mobility rates for the
general population are applicable to the subset of anglers. Since little if any data are available on
this issue, it may be best addressed in the uncertainty analysis, i.e., the second tier of the Monte
Carlo analysis.
The start date for the assessment will be 1999, the year in which the Human Health Risk
Assessment will be released. The assessment is not planning to model risks for individuals who
move into, or are born into the study area following 1999. If PCB levels in fish decline with
time, these individuals will have lower risks than the original exposed population.
The assessment anticipates that exposure duration will be one of the most difficult
exposure parameters to accurately characterize and the risk assessment will make assumptions
protective of public health. The assessment will explicitly describe the choices and
assumptions, comment on other alternative methods for addressing exposure duration, and
explain why they were not chosen.
E. PCB Cooking Losses
The assessment proposes reviewing the available literature on PCB losses during
cooking. Available studies will be evaluated to determine if they have adequately characterized
the extent of PCB losses during cooking to support a quantitative estimate of cooking losses
(both a point estimate and a distribution). Care will be taken in reviewing the studies to separate
those studies that reported raw fish mean portion concentration decreases and cooked fish meals
that reported contaminant mass loss. Depending on the findings, it will be determined whether to
include a quantitative estimate of PCB cooking losses in the subsequent quantitative risk
calculations (point estimate and Monte Carlo analysis), or to address this issue qualitatively. If
this issue is quantitatively addressed, the frequency of using each cooking method will be
included. PCB losses from trimming will not be evaluated since limited quantitative data on the
fish species of interest are available.
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While there does seem to be a consensus that some PCBs are lost during cooking, the
extent of this decrease has not been well characterized and thus quantitative estimates of cooking
losses are highly uncertain. Estimates of PCB losses from cooking are likely to be a function of
the cooking method, the temperature during cooking, the lipid content of the fish, the fish
species, the distribution of PCB congener species, the magnitude of the PCB contamination in
the raw fish, the extent to which lipids separated during cooking are consumed, the reporting
method, and the experimental study design. Experimental results have shown considerable
variability, both between various cooking methods and within the same method. Furthermore,
personal preferences for various cooking methods and other related habits (such as consuming
pan drippings) are poorly defined. Based on the scientific literature a determination will be made
as to an appropriate approach for assessing this effect.
The preliminary recommendation is to conservatively assume no loss from cooking when
calculating point estimates for central tendency and RME exposures. The uncertainty in PCB
losses during cooking will be evaluated in the second tier of the Monte Carlo analysis, using a
uniform distribution ranging from no loss to a loss of 74 percent, the maximum mean PCB loss
observed in all the PCB cooking loss studies.
F. PCB Concentrations for Deterministic and Monte Carlo Analyses
To evaluate PCB exposure via fish ingestion, the risk assessment will estimate fish PCB
concentration values (for total PCBs, Aroclor 1016. and Aroclor 1254 since a Reference Dose is
not available for Aroclor 1242), for each combination offish species representative of primary
fish consumed by the population (six species), river location (intervals from RM 153 to RM 195)
and time (one seTDf-values for each year, modeled for up to seventy years). The modeled values,
adjusted to represent standard fillet portions, will be based on the modeled concentrations based
on future river water and sediment concentration. Details of the method used in the final
determination of PCB concentrations will be provided. Based on the results from the modeling
report a determination will be made as to how to best segment the river stretches for the risk
assessment (see Section II.2A).
Both high-end and central exposure concentrations for this exposure pathway will be
calculated to evaluate risks to the reasonably maximally exposed individual and average
individual. To estimate a high end exposure point concentration, the assessment will: 1) use
PCB concentration data from the most contaminated species; 2) calculate the 95% Upper
Confidence Limit on the mean PCB concentration over a high end estimate of exposure
duration; and 3) use data from the most contaminated stretch of the Upper Hudson River. To
estimate a central exposure point concentration, the risk assessment will average PCB levels
over: 1) fish species (reflecting average angler fish consumption patterns), 2) time (reflecting a
central estimate of exposure duration), and 3) all locations in the Upper Hudson River.
The risk assessment will coordinate with other EPA Reassessment activities to obtain the
appropriate data. It is assumed that the concentration estimates provided by these parties will be
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either: 1) point values, or 2) probability distributions that characterize uncertainty in the
modeling or variability in the concentrations for each species. If uncertainty or variability
distribution information is available for each fish species, year, and location, the risk assessment
may use this information to select appropriate point concentration values for inclusion in the risk
analysis. For example, if the characterized uncertainty is substantial, the risk assessment will use
the arithmetic average fish PCB concentration value from the uncertainty distribution for each
fish species, year, and location for calculation of the central point estimate, and the
corresponding 95% upper confidence limit on the arithmetic mean (U. S. EPA, 1992c) from the
uncertainty distribution for calculation of the high end point estimate. If characterized variability
is substantial, the risk assessment will use the median fish PCB concentration from the
variability distribution for calculation of the central point estimate, and the 95th percentile of the
variability distribution for calculation of the high end point estimate.
For the two-stage Monte Carlo analysis, the risk assessment will calculate exposure
concentrations for each year separately, assuming that all anglers consume different fish species
in the same proportions. The simulation will employ any appropriate quantitative uncertainty
and variability information provided by the baseline modeling report. The risk assessment will
investigate two additional possibilities for the risk characterization. First, the risk assessment
will investigate the impact of assuming that some individuals consume only one (the most
contaminated) fish species. Second, the risk assessment will investigate the impact of assuming
that some anglers preferentially fish at hot spot locations.
G. Exposure Calculations From Fish Ingestion
High end and central tendency exposures from fish ingestion (the average daily dose for
non-cancer hazards, and the lifetime average daily dose for cancer risks) will be quantified using
the exposure point concentrations and point estimates for each exposure parameter, described
above, in standard EPA exposure equations (U. S. EPA. 1989).
H. Other Exposure Pathways
Inhalation of volatilized PCBs will also be evaluated using data from sites near the
Hudson River. Appropriate exposure assumptions based on inhalation rates and body weights
will be made in the assessment.
Exposures from recreational .pathways (incidental ingestion of sediment and dermal
contact with sediment and water) will also be quantified using data from the Phase 2 database
and a methodology that is as close as possible to the methodology used for Phase 1 risk
assessment. In addition, other routes of exposure not evaluated in the original Phase 1 risk
assessment based on inadequate data will also be evaluated to determine if adequate data is
currently available for the quantification of risks and hazards. Assuming the exposures from
these pathways are minimal compared to exposures resulting from fish consumption, it is
expected to exclude these recreational pathways from further evaluation (i.e., Monte Carlo
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analysis). Where appropriate, relevant text explaining the exclusion of less significant exposure
pathways from the Phase 1 report will be incorporated into this section of the Phase 2 report.
I. Calculation of Total Risks and Hazards
Consistent with EPA risk methodology (U.S. EPA. 1989 and 1986) the total risks and
hazards will be calculated for the reasonably maximally exposed individual and the central
tendency or average exposure. Risks and hazards will be added together across pathways and
presented in the risk characterization.
3. Toxicity Assessment
In the Phase 2 Hudson River risk assessment, the reference doses (RfDs) and cancer
slope factor (CSF) for PCBs established by EPA will be used (U. S. EPA, 1996c and 1998a-c).
Currently, there are RfDs for two individual Aroclor compounds. Aroclors 1016 and 1254, and
the three upper bound and central estimate CSFs for total PCBs. The data are currently available
on the Integrated Risk Information System (U.S. EPA, 1998a-c), the Agency's consensus
toxicity values. The IRIS values will be used in the assessment for the various routes of
exposure for both cancer and non-cancer health effects. The CSFs will be applied for appropriate
pathways. The sampling and modeling results will be evaluated to determine the most
appropriate Reference Dose.
The toxicity values will not be evaluated in the Monte Carlo analysis consistent with
EPA's policies (U. S. EPA,. 1997a).
The potential for endocrine effects will be evaluated using the current EPA assessment of
endocrine effects and other scientific studies (U.S. EPA, 1997b,c). At a minimum a qualitative
assessment of the currently available information on the potential effects of PCBs on the
endocrine system will be provided.
A section summarizing information on the toxicity of PCBs for both cancer and non-
cancer health effects will also be provided. The section will summarize appropriate information
from the IRIS chemical file and the most recent reported scientific studies. This section will also
discuss guidance values for PCBs derived by other federal agencies including the Agency for
Toxic Substances and Disease Registry (ATSDR, 1997) and the Great Lakes Sport Fish
Advisory Task Force (GLSFATF, 1993) and other appropriate documents.
4. Risk Characterization
The Risk Characterization section of the Phase 2 Upper Hudson Risk Assessment report
will closely follow the guidance put forth in the March 21, 1995 Risk Characterization Memo
(U.S. EPA. 1995b), reflecting transparency in the decision making process, clarity in
communication, consistency with other assessments, and reasonableness. This section will
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summarize the cancer risks and non-cancer hazards associated with PCB exposure under various
exposure scenarios. This section will also provide a statement of confidence, discussing the
strengths, limitations, and uncertainties inherent in the key scientific issues and science policy
choices involved in the toxicity assessment, exposure assessment, and risk conclusions.
Qualitative descriptive information will accompany numerical estimates of central tendency risks
and hazards, high end or reasonable maximum risks and hazards, and if available, risks for highly
exposed or susceptible subgroups. A detailed qualitative discussion of the uncertainties will be
included.
An enhanced Monte Carlo analysis will be performed to evaluate variability and
uncertainty in exposure parameters, using two phases to distinguish the impacts of variability and
uncertainty, where appropriate. The risk assessment will also provide a qualitative description of
additional uncertainties including the quality and quantity of available data, data gaps,
measurement uncertainties, model uncertainties, the verification of any models used, the use of
defaults, body burdens of PCBs. and plausible alternative approaches. The factors contributing
the greatest uncertainty will be explicitly identified in the risk characterization.
A. Calculation of Point Estimates of Central Tendency and High-End Individual Risks
Point estimates of risks and hazards will use standard EPA risk equations and exposure
estimates based on central tendency (average) and high-end exposure parameters (> 90th
percentile), as described in the preceding sections. The high-end and central tendency values
will be derived based on selection of appropriate percentiles from the distributions generated.
B. Risks for Highly Exposed Subgroups
Distinct ethnic subpopulations that may potentially consume unusually high quantities of
fish have not been identified living near the Upper Hudson River. Since subpopulations of
highly exposed and lesser exposed anglers will be represented in the distributions of risk
generated in the Monte Carlo analysis, it is not anticipated that further research will be conducted
to distinguish potential subgroups with unusually high exposures.
Theoretically, ethnic groups or small subpopulations of anglers may also preferentially
eat different species of fish than the general angling populations, but there are insufficient data
available on this issue. Therefore, as part of the uncertainty analysis, the second tier of the
Monte Carlo Analysis (described below), will use professional judgment to characterize worst-
case species specific consumption rates.
C. Monte Carlo Analysis
The Monte Carlo analysis will evaluate annual exposures on a year by year basis, starting
in 1999. The intake distributions will be based on the analyses of various exposure parameters
described in the preceding sections (II.2.A-I). The Monte Carlo analysis will assume that each
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individual consumes fish at the 90th percentile of the distribution for their age with appropriate
modification for bodyweight. The consumption percentile from year to year, chosen from the
distribution of consumption rates, thereby assumes that fish ingestion rates are perfectly
correlated each year. The Monte Carlo analysis will not assume a different ingestion rate each
year, which would assume that there is no correlation between yearly ingestion rates and
effectively average high-end consumers out of the analysis. Actual year to year ingestion rates
are probably correlated to a high degree, but not perfectly (100%); unfortunately no data are
available to quantitatively address this issue.
D. Additional Qualitative Discussions
Consistent with guidance from the March 21, 1995 Risk Characterization Memo (U.S.
EPA, 1995b), a qualitative discussion about other uncertainties which affect the risk results, such
as limitations in the models used to project future PCB concentrations in fish, database
uncertainties, available information concerning angler migration within the Hudson River area,
and other uncertainties inherent in each chosen parameter and distribution which were not
addressed in the uncertainty phase of the Monte Carlo analysis will be included in the document.
As appropriate, relevant text from reports such as the Modeling Report and the Data Evaluation
and Interpretation Report (U.S. EPA, 1997d) describing these uncertainties will be included in
the document.
E. Presentation of Results
The results of the analysis will be presented as described in the Risk Assessment
Guidance for Superfund Part D (U.S. EPA, 1997e). In addition, the Monte Carlo Analysis
information will be presented following the recommendations outlined in the EPA ''Policy for
Use of Probabilistic Analysis in Risk Assessment" (U.S. EPA, 1997a).
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III. MID-HUDSON RIVER HUMAN HEALTH RISK ASSESSMENT
SCOPE OF WORK
1. Plan, Synopsis & Objectives
This Scope of Work details the issues to be considered and the tasks to be completed in
preparing the Mid-Hudson River Human Health Risk Assessment. For each task or issue, a
description of the approach, an explanation of the analyses or modifications to the Upper Hudson
River risk assessment is provided (see Section II). This analysis will depend on the completion
of the Upper Hudson River risk and modeling work on the Lower Hudson River being conducted
under a grant from the Hudson River Foundation to Drs. Thomann and Farley. Individual
components of the proposed approach may be revised if additional data are identified in the
course of preparing the risk assessment.
The final human health risk assessment report will include a brief (1-2 pages) synopsis of
the 1991 preliminary risk assessment. The body of the report will contain an introduction, that
describes the objectives of the risk assessment for the Mid-Hudson.
2. Exposure Assessment
A. Fish Concentration Data.
The fish.cpncentrations will be developed using Mid-Hudson appropriate data from the
database for the Hudson River Reassessment RI/FS (U.S. EPA, 1995a); the Preliminary Model
Calibration report (U. S. EPA, 1996a); the Data Interpretation and Evaluation report (U. S. EPA,
1997d); and the Baseline Modeling report under development. The risk assessment will
summarize the results of these analyses and explain how concentration data was developed.
B. Fish Consumption Rates for the Mid-Hudson River
The risk assessment plans to characterize a distribution of fish consumption rates for the
Mid-Hudson River; high-end and central tendency point estimates will be identified as the
appropriate percentiles from the chosen distribution. While it is conceivable that fish ingestion
rates may differ between the Upper and Mid-Hudson because different fish species are present it
is unlikely that adequate data will be available to quantify this difference. Depending on data for
the Mid-Hudson risk assessment, the risk assessment may use the same distribution offish
ingestion rates developed for the Upper Hudson reflecting self-caught fish consumption from
multiple flowing fresh waterbodies. A complete description of the analysis offish ingestion rates
is included in Section II.2.B. The possibility that fish consumption rates differ in the Upper
Hudson versus the Mid-Hudson will be addressed using professional judgement in the
uncertainty phase of the Monte Carlo analysis.
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C. Species-Specific Fish Ingestion
The risk assessment intends to characterize species-specific intake rates for anglers
fishing in the Mid-Hudson River, since PCB levels in fish vary according to species. To
generate this information, the risk assessment will rely primarily on the Connelly (Connelly et
al., 1990, 1992, and 1996) and Clearwater data (Barclay, 1993), and other studies similar to the
approach used for the Upper Hudson (see Section II.2.C). Species-specific data will be derived
from a subset of "Mid-Hudson-like" flowing water bodies from the Connelly database (Connelly
et al., 1990, 1992 and 1996). ChemRisk's Maine study (ChemRisk, 1991) will be evaluated,
depending on the similarities between the Maine waterbodies and the Mid-Hudson River. Once
the relative contribution of each species to an individual's total fish intake from the Hudson is
characterized, it is planned to confirm that the characterization is consistent with all the available
data and that the species are in fact present in the Mid-Hudson. If any species offish are present
in the mid-Hudson and likely to be eaten, but modeled PCB concentration data is lacking, the
need to estimate PCB levels based on the fat content of the fish and available concentration data
from other similar species will be evaluated.
As in the Upper Hudson, there may be ethnic groups or small subpopulations of anglers
that preferentially eat different species of fish than the general angling population but there is
insufficient information available on this issue. This issue may be addressed as part of the
uncertainty analysis, the second tier of the Monte Carlo analysis, or using professional judgment
to characterize possible species-specific consumption rates.
D. Exposure Duration
The risk assessment will evaluate the available data on county mobility and angling
cessation to develop a realistic exposure duration for fishing in the Mid-Hudson River. While
Superfund risk assessments typically use the length of time that an individual remains in a single
residence as an exposure duration, such an estimate is not likely to be a good predictor of angling
duration, since an individual may move into a nearby residence and continue to fish in the same
location, or an individual may chose to stop angling irrespective of the location of his or her
home.
A more reasonable way to estimate exposure duration is to estimate the average length of
time before an individual moves far enough away from the mid-Hudson so that continued fishing
in the mid-Hudson would be unlikely. Connelly et al. (1990, 1992 and 1996) reported that
anglers traveled a mean distance of 34 miles to fish in the Upper and Lower Hudson River in
1988; however, there was considerable variability in the distances that people were willing to
travel. Also, it is unclear how relevant this mean distance of 34 miles is for the Mid-Hudson
River risk assessment, since the Connelly surveys were conducted while there were fishing
limitations in effect in the Mid-Hudson, and the traveling distance results are combined for the
Upper and Lower Hudson. Therefore, as a reasonable approximation, the risk assessment plans
to assume that Mid-Hudson River anglers fish in the Mid-Hudson as long as they live within the
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one of the counties bordering the Mid-Hudson, and that once they move outside of the bordering
counties, they would no longer be willing to travel the longer distance to the Mid-Hudson to fish.
The assessment will include a qualitative assessment of the size of the counties to support this
assumption. The risk assessment plans to analyze local and national county mobility data (the
In-Migration and Out-Migration Special Project Files from the Census Bureau (U. S. Department
of Commerce, 1992) as well as national census information such as the length of time people live
in a single residence (from the U. S. Census Bureau Summary Tape Population File 1A, U. S.
Bureau of Census, 1992) to generate a reasonable estimate of how long people remain living
within the counties bordering the Mid-Hudson. This is similar to the approach used for the
Upper Hudson, but considers different counties.
The risk assessment will attempt to incorporate the likelihood that an angler may
voluntarily choose to stop fishing, based on an analysis of the percent of licensed anglers in the
New York State general population at each age. This part of the analysis will be completed as
part of the Upper Hudson risk assessment.
To the extent possible, the risk assessment will also investigate whether the mobility
rates for the general population are applicable to the subset of anglers. Since little if any data are
available on this issue, it may be best addressed in the uncertainty analysis, i.e., the second tier of
the Monte Carlo analysis.
As in the Upper Hudson, the risk assessment is not planning to model risks for
individuals who move into, or are bom into the study area following 1999, the start date of the
risk assessment. Since PCS levels in fish are declining with time, these individuals will have
lower risks than the original exposed population.
It is anticipated that exposure duration will be one of the most difficult exposure
parameters to accurately characterize. Therefore, the risk assessment will explicitly describe the
choices and assumptions, comment on other alternative methods for addressing exposure
duration, and explain why they were not chosen.
E. PCB Cooking Losses
For the Mid-Hudson, the risk assessment procedures used in the analysis of PCB cooking
losses for the Upper Hudson Risk Assessment is proposed. A complete description of our
analysis of cooking losses is included in the Upper Hudson Scope of Work (see Section II.2.E).
F. PCB Concentrations for Deterministic and Monte Carlo Analyses
To evaluate PCB exposure via fish ingestion, the risk assessment will estimate fish PCB
concentration values (for total PCBs, Aroclor 1016 and Aroclor 1254 since a Reference Dose for
Aroclor 1242 is not available), for each combination offish species (six species), river location
(RM 70 to RM 153) and time (one set of values for each year, modeled for up to seventy years).
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The modeled values, adjusted to represent standard fillet portions, will be based on the modeled
concentrations based on future river water and sediment concentrations. Pathway specific central
and high-end exposure concentrations will be calculated. To estimate central tendency exposure
point concentrations (i.e., average exposure), the risk assessment will average PCB levels over:
1) fish species (reflecting average angler fish consumption patterns), 2) time (reflecting a central
estimate of exposure duration), and 3) all locations in the Mid-Hudson River. To estimate a high
end exposure point concentrations, the risk assessment will: 1) use PCB concentration data from
the most contaminated species; 2) calculate the 95% Upper Confidence Limit on the Mean PCB
concentration (U.S. EPA, 1992c) over a high end estimate of exposure duration; and 3) use data
from the most contaminated stretch of the Mid-Hudson River.
The risk assessment will coordinate with other EPA Reassessment activities (U.S. EPA,
1995a, 1996a, and 1997d) on the project to obtain the appropriate data. It is assumed that the
concentration estimates provided will be either: 1) point values, or 2) probability distributions
that characterize uncertainty in the modeling or variability in the concentrations for each species.
If uncertainty or variability distribution information is available for each fish species, year, and
location, the risk assessment may use this information to select appropriate point concentration
values for inclusion in the risk analysis. For example, if the characterized uncertainty is
substantial, the risk assessment will use the arithmetic average fish PCB concentration value
from the uncertainty distribution for each fish species, year, and location for calculation of the
central point estimate, and the corresponding 95% upper confidence limit on the arithmetic mean
from the uncertainty distribution for calculation of the high end point estimate. If characterized
variability is substantial, the risk assessment will use the median fish PCB concentration from
the variability distribution for calculation of the central point estimate, and the 95th percentile of
the variability distribution for calculation of the high end point estimate.
For the two-stage Monte Carlo analysis, the risk assessment will calculate exposure
concentrations for each year separately, assuming that all anglers consume different fish species
in the same proportions. The simulation will employ any appropriate quantitative uncertainty
and variability information provided by the baseline modeling report. The risk assessment will
investigate two additional possibilities for the Mid-Hudson risk characterization. First, the risk
assessment will investigate the impact of assuming that some individuals consume only one (the
most contaminated) fish species. Second, the risk assessment will investigate the impact of
assuming that some anglers preferentially fish at hot spot locations.
G. Exposure Calculations From Fish Ingestion
High end and central tendency exposures from fish ingestion (the average daily dose for
non-cancer hazards, and the lifetime average daily dose for cancer risks) will be quantified using
the exposure point concentrations and point estimates for each exposure parameter, described
above, in standard EPA exposure equations (U. S. EPA. 1989).
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H. Other Exposure Pathways
Inhalation of volatilized PCBs will also be evaluated using available data from sites near
the Hudson River where available. Appropriate exposure assumptions based on inhalation rates
and body weights will be made in the assessment.
Exposures from recreational pathways (incidental ingestion of sediment and dermal
contact with sediment and water) will also be quantified using data from the Phase 2 database
and methodologies that are as close as possible to the methodology used for Phase 1 risk
assessment. In addition, other routes of exposure not evaluated in the original Phase 1 risk
assessment based on inadequate data will also be evaluated to determine if adequate data is
available currently for the quantification of risks and hazards. Assuming the exposures from
these pathways are minimal compared to exposures resulting from fish consumption, it is
expected to exclude these recreational pathways from further evaluation (i.e., Monte Carlo
analysis). Where appropriate, relevant text referring to the exclusion of less significant exposure
pathways from the Phase 1 report will be incorporated into this section of the Phase 2 report.
I. Calculation of Total Risks and Hazards.
Consistent with EPA risk methodology (U.S. EPA, 1989 and 1986) the total risks and
hazards will be developed for the reasonably maximally exposed individual and the central
tendency or average exposure. Risks and hazards will be added together across pathways and
total risks and hazards presented in the risk characterization.
~^ -\_
3. Toxicity Assessment
As in the Upper Hudson risk assessment (see Section II.3), the Mid-Hudson risk
assessment will use the reference doses (RfDs) and cancer slope factor (CSF) for PCBs
established by EPA. The values will be developed using the chemical and Aroclor specific
chemical files on the Integrated Risk Information System (U.S. EPA, 1998a, b,c), the Agency's
consensus database on toxicity. Endocrine effects analysis identified in the Upper Hudson River
assessment will also be addressed here.
The toxicity values will not be evaluated in the Monte Carlo analysis in conformance
with EPA's guidance (USEPA, 1997a).
The section summarizing information on the toxicity of PCBs for both cancer and non-
cancer health effects for the Upper Hudson River risk assessment will also be provided.
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4. Risk Characterization
The Risk Characterization section of the Phase 2 Mid-Hudson Risk Assessment report
will closely follow the guidance put forth in the March 21, 1995 Risk Characterization Memo
(U.S. EPA, 1995b), reflecting transparency in decision making process, clarity in
communication, consistency, and reasonableness. This section will summarize the risks and
provide a statement of confidence, discussing the strengths, limitations, and uncertainties
inherent in the key scientific issues and science policy choices involved in the toxicity
assessment, exposure assessment, and risk conclusions. Qualitative descriptive information will
accompany numerical estimates of central tendency risks and hazards, high end risks and
hazards, population risks, and if available, risks for highly exposed or susceptible subgroups. A
detailed discussion of the uncertainties will be included based on the enhanced Monte Carlo
analysis to evaluate variability and uncertainty in exposure parameters, using two phases to
distinguish the impacts of variability and uncertainty. A qualitative description of additional
uncertainties including the quality and quantity of available data, data gaps, measurement
uncertainties, model uncertainties, the verification of any models used, the use of defaults, and
plausible alternative approaches will also be described. The factors contributing the greatest
uncertainty will be explicitly identified.
A. Calculation of Point Estimates of Central Tendency and High-End Individual Risks
Calculated point estimates of risks using standard EPA risk equations (U.S. EPA, 1989)
and exposure estimates based on central tendency and high-end exposure parameters, as
described in the preceding sections will be developed. The high-end and central tendency values
will be derived using selected percentiles from the distributions generated.
B. Risks for Highly Exposed Subgroups
Since subpopulations of highly exposed and lesser exposed anglers will be represented in
the distributions of risk generated in the Monte Carlo analysis, the risk assessment will not
attempt to further distinguish any hypothetical subgroups with unusually high exposure.
However, if any distinct ethnic subpopulations living near the Mid-Hudson River are identified
who might consume high levels offish from the Mid-Hudson in the absence of any fishing
restrictions, a worst-case, bounding scenario to estimate the risks for this subgroup may be
developed.
Theoretically, ethnic groups or small subpopulations of anglers may also preferentially
eat different species of fish than the general angling population, but there are no data available on
this issue. Therefore, as pan of the uncertainty analysis, the second tier of the Monte Carlo
analysis (described below), will use professional judgment to characterize plausible worst-case
species-specific consumption rates.
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C. Monte Carlo Analysis
As in the Upper Hudson Risk Assessment, the Monte Carlo analysis will evaluate annual
exposures on a year by year basis, starting in 1999. The intake distributions will be based on the
analyses of various exposure parameters described in the preceding sections. The Monte Carlo
analysis will assume that each individual consumes fish at the 90th percentile of the distribution
for their age with appropriate modification for bodyweight. The consumption percentile from
year to year, chosen from the distribution of consumption rates, thereby assumes that fish
ingestion rates are perfectly correlated each year. The Monte Carlo analysis will not assume a
different ingestion rate each year, which would assume that there is no correlation between
yearly ingestion rates and effectively average high-end consumers out of the analysis. Actual
year to year ingestion rates are probably correlated to a high degree, but not perfectly (100%);
unfortunately no data are available to quantitatively address this issue.
D. Additional Qualitative Discussions
Consistent with guidance from the March 21, 1995 Risk Characterization Memo (U.S.
EPA, 1995b), the risk assessment will also provide qualitative discussions about other
uncertainties which affect the risk results, such as limitations in the models used to project future
PCB fish concentrations, database uncertainties, and other uncertainties inherent in each chosen
parameter and distribution which were not addressed in the uncertainty phase of the Monte Carlo
analysis. To the extent possible, relevant text from other reassessment reports, such as the
modeling, data evaluation and interpretation report, and database reports, will be incorporated
into the risk assessment document (U.S. EPA, 1995a, 1996a and 1997d).
E. Presentation of Results
The results of the analysis will be presented following the Risk Assessment Guidance for
Superfund Part D (U.S. EPA, 1997d) guidance. In addition, the Monte Carlo Analysis
information will be presented following the recommendations outlined in the EPA ''Policy for
Use of Probabilistic Analysis in Risk Assessment" (U.S. EPA, 1997a).
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IV. REFERENCES
Agency for Toxic Substances and Disease Registry (ATSDR) (1997) Toxicological Profile for
Polychlorinated Biphenyls. Atlanta, GA: U. S. Department of Health and Human
Services, U. S. Public Health Service.
Barclay, B. (1993) Hudson River Angler Survey. Hudson River Sloop Clearwater, Inc.,
Poughkeepsie, New York.
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